LCD backlight control question

We are using a Newhaven NHD-7.0-800480EF-ASXN#-CTP display with a Colibri iMX6. Everything works great except that I can’t get the LCD backlight to turn off by using the Power applet in the control panel.

It looks like we are doing everything correctly according to this post:
https://www.toradex.com/community/questions/11078/lcd-backlight-control-in-win-ce.html

Specifically, from the Iris carrier connector X3, pin 5 (BL_ON) is connected to pin 31 (DISP) of the Newhaven display. X3 pin 5 is SODIMM # 71, which is the default backlight enable pin according to that post.

I have set the power properties as suggested:
721-power.jpg

The only thing that may be missing are registry settings. That post I referred to says this:

By default we use SODIMM Pin no. 71 as
backlight enable pin. You can change
this pin and its polarity as per your
hardware configuration through below
display driver registry entry :

HKEY_LOCAL_MACHINE\SOFTWARE\NVIDIA
Corporation\NVDDI\LCD

“BL_GPIO”=dword: x (where x = GPIO No.
of SODIMM Pin you want to use)

“BL_POL”=dword:0 or 1

“DISP_GPIO”=dword: x

“DISP_POL”=dword:0 or 1

I have not added any of this information to the registry, as I understand that the default should be sufficient. Are these registry settings needed if we just use the defaults?

If you have any ideas what we should try to resolve this, it would be very much appreciated.

@guzoo,

Thank you for contacting support.

There is an issue of backlight implementation. Please refer https://developer.toradex.com/software/windows-embedded-compact/imx6-wec-software/release-details?view=all&issue=31672 and https://developer.toradex.com/software/windows-embedded-compact/imx6-wec-software/release-details?view=all&issue=32260 for more information.

Could you please wait for 1 or 2 weeks. we are planning to release 1.3B4 release soon.

Hi and thanks for the info.

I just tried controlling the back-light using the GPIO tool and it works fine when you explicitly change the state of GPIO 90 (SODIMM 71). Our application is turn-key so I can actually implement the timeout etc. in our app and not have to rely on the OS to do this for us.

After your updates we may reconsider our approach.

@guzoo,

Glad to know you have implemented a workaround in your application.
Best regards and good luck.